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Li-Tect: 3D Monitoring and Shape Detection using Visible Light Sensors
摘要： In this paper, we propose Li-Tect, an algorithm to detect the shape of an object located in an indoor environment using low cost optical elements through sensing the environment's light. The algorithm analyzes, relying on the predictability of optical propagation paths, how much light is expected to propagate in the absence of obstructions caused by the presence of an object. Then, based on the received light when the object is in the room, the algorithm infers the shape of the object. In addition, the algorithm considers the reflected paths from surfaces in order to determine the object's estimated shape. We study five different scenarios characterized by different levels of complexity, room sizes and a range of reflection nodes. The algorithm is also tested in a real prototype where several experiments are carried out in two scenarios to demonstrate the capabilities of Li-Tect in two and three dimensional monitoring and shape detection cases. Finally, the results show that the shape and the detection of objects in the scenarios can be easily acquired with high accuracy, even if the number of transceivers is reduced.
关键词： Visible Light Sensors,Ray Tracing,Monitoring,Visible Light Communications,Shape Detection
更新于2025-09-23 15:21:21
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Dimming Control Systems Based on Low-PAPR SCFDM for Visible Light Communications
摘要： In this paper, the efficient dimming control systems based on single-carrier frequency-division multiplexing (SCFDM) are proposed for visible light communications (VLC). By virtue of the strengths of the low peak-to-average power ratio and the inherent resistance to high-frequency distortion, the proposed SCFDM-based dimming control schemes are adaptive to the bandwidth-limited and linearity-limited VLC system, thus supporting the wide dimming range for different illumination requirements. Two SCFDM-based VLC systems with dimming control including asymmetrical hybrid optical SCFDM (AHO-SCFDM) and DC-biased optical SCFDM (DCO-SCFDM) are proposed. For AHO-SCFDM with spectral efficiency of 1.75 bit/s/Hz and DCO-SCFDM with spectral efficiency of 2 bit/s/Hz, the 20% wider dimming range can be achieved than their orthogonal frequency-division multiplexing (OFDM) based counterparts, respectively. Meanwhile, the two proposed schemes can also achieve 24.8% and 31.3% gains of average spectral efficiency under the same dimming range compared with their counterparts, respectively. For an overall analysis, SCFDM shows the feasibility and superiority for dimming control systems.
关键词： light emitting diode,Visible light communication,single-carrier frequency-division multiplexing,dimming control,orthogonal frequency-division multiplexing
更新于2025-09-23 15:21:21
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Bio-inspired Z-scheme g-C3N4/Ag2CrO4 for efficient visible-light photocatalytic hydrogen generation
摘要： Due to low charge separation efficiency and poor stability, it is usually difficult for single-component photocatalysts such as graphitic carbon nitride (g-C3N4) and silver chromate (Ag2CrO4) to fulfill photocatalytic hydrogen production efficiently. Z-scheme charge transport mechanism that mimics the photosynthesis in nature is an effective way to solve the above problems. Inspired by photosynthesis, we report Ag2CrO4 nanoparticles-decorated g-C3N4 nanosheet as an efficient photocatalyst for hydrogen evolution reaction (HER) with methanol as sacrificial agent. The formation of Z-scheme g-C3N4/Ag2CrO4 nanosheets photocatalysts could inhibit the recombination of photogenerated electron-hole pairs, promote the generation of hydrogen by photosplitting of water. The experiment results indicate that g-C3N4/Ag2CrO4 nanocomposites present enhanced photocatalytic activity and stability in the H2 evolution of water splitting. And the nanocomposites g-C3N4/Ag2CrO4(23.1%) show the 14 times HER efficiency compared to that of bare g-C3N4.
关键词： visible-light,Z-scheme,hydrogen production,g-C3N4,Ag2CrO4,photocatalysts
更新于2025-09-23 15:21:21
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A critical review on visible-light-response CeO2-based photocatalysts with enhanced photooxidation of organic pollutants
摘要： Organic pollutants’ treatment in wastewater has attracted extensive attention due to its degradation-resistance and potentially hazardous to human health. Some organic matters such as persistent organic pollutants (POPs) could exist in environment and resist to decomposition, which may cause chronic intoxication or even cancers. Because photocatalytic technique is efficient, nontoxic, and cost-effective to degrade organic pollutants, some semiconductors including TiO2 and ZnO as photocatalysts have aroused wide public concern. CeO2 has been reported as an efficient photocatalyst in contrast to TiO2 owing to its high oxygen storage, eco-friendly properties and photostability. But inefficient utilization of solar energy due to its intrinsic wide bandgap restrains its further application in real environmental pollutant treatment. In order to improve photocatalytic performances of CeO2, some modifications have been developed such as doping ions, coupling with semiconductor and construction of CeO2-based solid-solution. The purpose of this review is to introduce these techniques, reveals its fundamental mechanisms and the recent researches about photodegradation of organic pollutants in wastewater over CeO2-based photocatalysts. Besides, this review will evaluate the photocatalytic performance for organic pollutants and outlook the challenges and prospects in the future.
关键词： Modification,CeO2,Visible-light-response,Photodegradation,Organic pollutants
更新于2025-09-23 15:21:21
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Rational band design in metal chalcogenide Ba6Zn6HfS14: splitting orbitals, narrowing forbidden gap and boosting photocatalyst property
摘要： The insufficient light sources absorption often limits photocatalyst applications of metal chalcogenides because of their excessively broad band gap. Thus, it is necessary to discover and design a compound with rational band gap. Here, a new visible-light photocatalyst, Ba6Zn6HfS14, is prepared through the traditional high temperature solid-state reaction. A set of experiments on the visible-light decomposition of methylene blue demonstrated that the photocatalytic efficiency of Ba6Zn6HfS14 (0.00761 min-1) is improved, compared to that of Ba6Zn6ZrS14 (0.00553 min-1) which proved to be a previously reported visible-light photocatalyst with similar structure. The UV-visible reflection spectra demonstrated the energy gap of Ba6Zn6HfS14 (E1=1.45eV; E2 =2.55eV) is smaller than that of Ba6Zn6ZrS14 (E1 = 1.78eV; E2 = 2.50eV; E3 = 2.65eV). The Ba6Zn6HfS14 absorbs more visible light and exhibits preferably photocatalytic activity. The origin of splitted energy bands were elucidated via the first calculations.
关键词： band gap engineering,chalcogenides,visible-light photocatalyst
更新于2025-09-23 15:21:21
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IEEE Access Special Section Editorial: Optical Wireless Technologies for 5G Communications and Beyond
摘要： Wide bandwidth and dense spatial reuse are of extreme importance for future wireless communication networks, including 5G and beyond. In particular, these properties are important to enable future wireless networks to cope with the explosive increase in the demand for high data-rate communications. Optical wireless communications (OWC) is a promising technology for achieving this goal due to the abundant reusable license-free optical spectrum. This potential of OWC attracted significant global attention both from communications and optoelectronics viewpoints, and continues to do so.
关键词： 5G,beam-steering,mixed FSO/fiber backhauling,OFDM,MIMO,Optical wireless communications,vehicle-to-vehicle communications,free-space optics,vehicle-to-infrastructure communications,network-layer aspects,visible-light communications
更新于2025-09-23 15:21:21
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RECENT APPLICATIONS IN ORGANIC SYNTHESIS OF VISIBLE LIGHT PHOTOREDOX CATALYSIS
摘要： RECENT APPLICATIONS IN ORGANIC SYNTHESIS OF VISIBLE LIGHT PHOTOREDOX CATALYSIS. In the past few years, photoredox catalysis has become a powerful tool in the field of organic synthesis. Using this efficient method, it is possible to excite organic compounds from visible light and attain alternative mechanistic pathways for the formation of chemical bonds, a result which is not obtainable by classical methods. The rapid growth of work in the area of photoredox catalysis is due to its low cost, broad chemical utility protocols, and, especially, its relevancy from the green and sustainable chemistry viewpoints. Thus, this study proposes a brief theoretical discussion of and highlights recent advances in visible-light-induced photoredox catalysis through the analysis of catalytic cycles and intermediates.
关键词： visible light,photoredox catalysis,organocatalysis,organic synthesis,transition metals
更新于2025-09-23 15:21:21
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Control of Spatially Homogeneous Distribution of Heteroatoms to Produce Red TiO2 Photocatalyst for Visible-Light Photocatalytic Water Splitting
摘要： The strong band-to-band absorption of photocatalysts spanning the whole visible light region (400-700 nm) is critically important for solar-driven photocatalysis. Although it is actively and widely used as photocatalyst for various reactions in the past four decades, TiO2 has a very poor ability to capture the whole-spectrum visible light. Here, by controlling the spatially homogeneous distribution of boron and nitrogen heteroatoms in anatase TiO2 microspheres with a predominance of high-energy {001} facets, a strong visible light absorption spectrum with a sharp edge beyond 680 nm is achieved. The red TiO2 with the homogeneous doping of boron and nitrogen obtained shows no increase in defects like Ti3+ that are commonly observed in doped TiO2. More importantly, it has the ability to induce photocatalytic water oxidation to produce oxygen under the irradiation of visible light beyond 550 nm and also photocatalytic reducing water to produce hydrogen under visible light. These results demonstrate the great promise of using the red TiO2 for visible light photocatalytic water splitting and also provide an attractive strategy for realizing the wide-spectrum visible light absorption of wide-bandgap oxide photocatalysts.
关键词： Titanium Dioxide,Photocatalysis,Water Splitting,Homogeneous Doping,Visible Light
更新于2025-09-23 15:21:21
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The fabrication of floating Fe/N co-doped titania/diatomite granule catalyst with enhanced photocatalytic efficiency under visible light irradiation
摘要： Powdery photocatalyst has long been studied, yet its several disadvantages such as light-harvesting and recyclability in suspension system are the bottlenecks for practical application. The recent report on floating photocatalyst provided an alternative method to solve the above problem. In this work, TiO2 nanoparticles were co-doped by iron and nitrogen, and then dispersed onto natural porous mineral diatomite via sol-gel method. The composite powder was granulated to produce floating granule catalyst (Fe/N co-doped TiO2/diatomite hybrid granule), denoted as FN-TDHG. Its various physicochemical properties such as light absorbance, crystallinity, surface condition as well as morphology were systematically analyzed. The synergy between Fe and N dopants, as well as diatomite and TiO2 were studied. The photoactivity of FN-TDHG was investigated via the degradation towards tetracycline (TC) solution under visible light irradiation, and then the optimal co-doping amount and granule dosage were determined. The optimal granule catalyst presented its removal rate of TC as 96.5% within 150 min. Moreover, floating FN-TDHG could simply be filtrated from the surface of water matrix, and presented good reusability after 5 repetitions. This photocatalytic granule is hopefully considered suitable to be applied in environmental remediation.
关键词： Fe/N co-doped,Diatomite,Floating,Visible light,Tetracycline
更新于2025-09-23 15:21:21
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Assembly of graphene on Ag3PO4/AgI for effective degradation of carbamazepine under Visible-light irradiation: Mechanism and degradation pathways
摘要： A highly efficient visible-light-driven photocatalyst Ag3PO4/AgI-Graphene (Ag3PO4/AgI-G) was synthesized through a chemical coprecipitation procedure. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were performed to study the physicochemical structural of the photocatalysts. The photocatalytic activity of the samples was examined by the carbamazepine (CBZ) degradation under artificial visible light and natural sunlight irradiation. Experimental results indicated that the introduction of low mass content of graphene enhanced the photocatalytic performance of Ag3PO4/AgI, and the photocatalytic degradation efficiency of CBZ over Ag3PO4/AgI-3%G (mass ratio of graphene : Ag3PO4/AgI = 3:100) reached 93.06% within 21 min, which was much higher than that over pure Ag3PO4 (26.92%) and Ag3PO4/AgI (74.38%). UV-vis diffuse reflectance spectra, photoluminescence (PL) spectra, transient photocurrent responses and electrochemical impedance spectra (EIS) of the samples were conducted to verify the high photocatalytic performance of the Ag3PO4/AgI-3%G. In addition, possible photocatalytic degradation pathways of CBZ were proposed based on the analysis of transformation products during the reaction. The reactive species trapping experiments and Electron spin resonance (ESR) analysis demonstrated that h+ and ·O2- were the main active oxidant species responsible for CBZ photodegradation. The photocatalytic degradation mechanism of CBZ over Ag3PO4/AgI-3%G under visible light irradiation was schematically proposed. This study not only provides a new technique for the synthesis of Ag3PO4-based photocatalysts with high photocatalytic activity, but also demonstrates that the Ag3PO4/AgI-3%G composite could be a promising photocatalyst for the treatment of waters containing CBZ.
关键词： Photocatalytic degradation,Carbamazepine,Z-scheme,Graphene,Ag3PO4/AgI,Visible light
更新于2025-09-23 15:21:21